Polyurethane catalyst composition and method for preparing cellular polyurethane using same



United States Patent Oillice 3,044,971 Patented July 17, 1962 IULYURl Il]N15 CA'I /\l.\ COMPOSITION AND METHOD OR PREPARING CELLULAR POLY- URETHANE USING SAME Samuel l'olis. Pittsburgh, lzL. assignor f0 Mobay Chemicirl turnpany. Pittsburgh, Pin, a corporation of Delaare No Drawing. Filed Mar. 13, 1959, Ser. No. 800,096

('lairns. (Cl. 260-) This invention relates gcnerz lly to the preparation of cellular polyurethane plastic. and. more particularly, to it method for making improved cellular polyurethanes and to tr novel catulyst mixture thercl'or.

it has been proposed heretofore to react an organic polyis ate with an organic compound having groups containing hydrogen atoms reactive with an -NCO group to form :r polyurethane pla tic having :1 porous structure. Although it has been proposed to prepare a ecl lulzrr' polyurethane by such a process when using a polytrllt'ylenc ether glycol. ccllulur' pohurethanes prepared from polyesters ohttrined by esterilicution of ti polyhydric alcohol and It polyctulroxylic acid have. until recently. met with the most commereinl succe s. Cellular polyurcthrtnes are ordinarily prepared from a polyester by a onc stcp PFUL'L\\ in which the polycster. organic polyisocyautrte. cataly t. water and other components are all miwd together at one time. It has been necessary in order to produce no entirely satisfactory ccllulnr polyurethane from it polyulkylcrre ether alcohol, however. to prepare the product in n two-step process: In such a process. the polyztllq lcnc cthcr alcohol is reacted in a First step under sub tantially anhydrous conditions to produce .1 prcpolyrnrr or udduct hating terminal -NLO groups. "1 hen in a second stern the prcpolymer is mixed with water and chemical reaction is effected between the water and terminal --N(() groups of the prcpo ynrcr and monomeric polyisocyzrnate, such :is. for example, toluylene tli socyzmatc. which is present in the mixture. Carbon dioxide is formed during this reaction and becomes entrirppcd in the viscous reaction mixture as chain-lengthening of the prcpohmer occurs. The resulting product has i. porous structure.

it is an object of this invention to provide a method for making n CClllllLll polyurethane plastic from a poly nlkylenc ether alcohol by a one-step method. Another object of the invention is to provide 111 improved meth oil for mailing cellular polyurethanes when using a polyalltylcne ether alcohol of high molecular weight where in the polyalkylenc ether alcohol, organic polyisocyanate, crttalyst. blowing agent. and other components of the re action mixture can all be mixed together simultaneously. Still another ohicct of the invention is to provide an ink proved catalyst mixture which permits the preparation of a cellular polyurethane piuslic from tr polyttlkylcnc ether ulcohol by .r process in which all of the components of the reaction mixture may be mixed together substantially simultaneously. more pecific object of the invention is to provide 21 method formatting cellular polyurethanes in which all of the reaction components are mixed togetltcr substantially simultaneously and the cellular polyurethane thus ubtztined has improved heat stability.

the foregoing objects and others which will become apparent from the following disclosure are accomplished in accordance with this invention. generally speaking, by providing a method for making a cellular polyurethane by reacting a polynlkylcne ether alcohol having from 2 to 4 hydroxyl groups and a 1llOlClllitr weight of at least about 500 with an organic polyisocynnate in the presence of a mixture containing as the only material required as a catalyst from about 0.01 to about 0.1 part of Stan nous chloride or an orgzrno-tin compound, defined in more detail hereinafter, from about 0.2 to about 1.5 parts of either Ncthyl morplroline or N-nrethyl morpholr'ne and from about 0.1 part to about 0.3 part triethylene diamine per 100 parts by weight polyalkylene ether alcohol. The invention is predicated upon the discovery that an organic polyisocynnatc, a polyalkylene ether alcohol hay-- ing from 2 to 4 hydroxyl groups and a molecular weight of at least about 500, water or other suitable blowing agent. catalyst and emulsifier or other components of a reaction mixture can all be mixed together substantially simultaneously and that the resulting product will be heat stable even at ('1 temperature of about 140 C. or higher provided the catalyst mixture does not vary appreciably from the composition set forth immediately hereinbefore. The ratio of the components of the catalyst must be 0.01 to 0.1 stannous chloride or organo-tin compound per 0.2 to 1.5 parts N-alkyl morpholine per 0.1 to 0.3 part trietlrylene diamine in order for the reaction rate to be satisfactory and for the product to have desirable physical characteristics. It has been found that if the amount of stannous chloride or organo-tin compound is reduced below the minimum amount set forth above. chemical reaction does not proceed at a rate suitzrble to permit mixing of all of the components together at one time. 11 on the other hand, the amount of stannous chloride or organotin compound is increased above about. 01 part per parts of the polyalkylene ether alcohol. the resulting product is subject to substantial degradation at temperatures of C. or above.

Organotin compounds suitable for use as a component of the catalyst mixture are a stannous salt of a :arboxylic acid having from 1 to 8 carbon atoms including stannous octoate. stannous oleate and the like, a tritrlkyl tin oxide in which the alkyl groups contain from 1 to 8 carbon atoms, a diatkyl tin chloride in which the alkyl groups contain from 1 to 8 carbon atoms, a dialkyl tin oxide in which the alkyl groups contain from 1 to 8 carbon atoms or a dialkyl tin salt of a carboxylic acid having from 1 to 18 carbon atoms in which the alkyl groups contain from 1 to 8 carbon atoms including dibutyl tin dilaurate, dibutyl tin diacetnte, diethyl tin diacetate, dibexyl tin dr'acetate and dibutyl tin-di(2 ethylhexoate). The invention thus contemplates a catalyst mixture for use in the preparation of cellular polyurethanes containing as the sole components added only for catalytic purposes from about 0.01 part to about 0.1 part of one of these organo-tin compounds or stannous chloride or mixtures thereof, from about 0.2 to about 1.5 parts N-ethy] morpholine or N-methyl morpholr'ne or mixtures thereof and from about 0.1 part to about 0.3 part triethylcne diamine per 100 parts by weight polyalkylenc ether alcohol. Preferably the stannous chloride or organo-tin compound of the catalyst mixture is mixed with the polyalkylene ether alcohol before the other components are added and the tertiary amines are added at the same time as the polyisocyanate but as a separate stream. Alternatively, the tin compound can be mixed with the two tertiary amines and the resulting mixture then mixed with the polyalkylene ether alcohol. organic polyisocyanate and other components of the reaction mixture. Of the various organo-tin compounds disclosed herein as suitable for the process. it has been found that best results are obtained with dibutyl tin-di(2 ethylhexoate) and dibutyl tin-diacetate. Preferably, the catalyst mixture should contain about 0.05 part organetin compound. about 0.5 part N-ethyl morpholine and about 0.2 part triethylene diamine per 100 parts polyalkylene ether alcohol. It is, of course, possible to mix a stabilizer and/0r emulsifier or other additive component to the catalyst mixture.

Best results are obtained when the reaction mixture contains an organo siloxane as a stabilizer. Any silicone sito' -pt .ll mntt" "eir R, R and R" are alkyl radicals having 1 to 4 .aa atoms; p. q and reach have a \alue of from 4 to .l". tfi H Ol is a mixed polyoxyelhylcne oxypropyb w i; up llflllitlllllllg from 15 to l) oxyethylene units and trout ll to 15 mypropylcne units with 2, equal to from about 26 to aboul 34 is particularly advantageousv Organo silicone compounds of this type and a method for maltiuu them are disclosed in US. Patent 2.834.748.

Although the catalyst mixture is mod advantageous because of its utility in a onctep process where all of he ingredients ol the reaction mt\lnrc are brought together substantially simultaneously. the catalyst mitture can also be used in a [WU-\[CP process in which a prcpolymer is formed in a first step under substantially anhydrous CDt'lLllllUl'ts by reaction between a polyalltylcne ether alcohol and an organic polyisocyanate. Then in a second step. the resulting prepolymer having terminal -NCO groups is reacted with water to form it cellular product. The amount ot catalyst u ed in the two-step process is substantially the same as that used in the onestcp process. The catalyst can be added to the mixture n either step but it is preferred to add it in the second tep. The novel catalyst mixture is advantageous oyer heretofore known catalysts even in the two-step process because it results in the formation of a heat-stable product having improved softness and being substantially free from objectionable odors within a very short period of time after it is formed.

Any suitable polyalltylene ether alcohol having from J to 4 hydroxyl groups and a molceulnr weight of at least about Sllll may be used in the process provided by this invention. Examples of suitable polyalltylcne ether alcohols include those prepared by condensation of an alkylene oxide having from 1 to 5 carbon atoms, such as. for example. polypmpylene ether glycol. polyethylene ether glycol, polybutylcne ether glycol or a glycol prepared from a mixture of two or more all-ylene oxides. such as. for example. ethylene oxide. propylene oxide, butylcne o tidc. amylene oxide. and the like. A polyalkylenc ether glycol prepared by polymerization of tetra hydrol'uran or mixtures of these cthcr glycols with the condensation product of an alltvlenc oxide may also be used. Moreover, the condensation product of an alltylene oxide having from 2 to 5 carbon atoms and a polyhy'dric alcohol having from 3 to 4 hvdrotyl groups. such as. for example, glycerine. trimethylol propane. tricthunolnmine, triethylolpropane. pcntacrythrilol, hesunetriol and the like, may be used provided the molecular weight of the condensation product is at least about Still. The polyalkylene ether alcohols may be prepared by any known condensation process. such as. for example. by the process described by Wart? in I859 and in Encyclopedia of Chemical Technology." vol. 7. pp, 157 to 262. published by lnterscience Publishers. Incorporated. 195], or in US Patent b92145). A mixture of one of these polyalltylene ether alcohols and a monomeric polyhydric alcohol such as. for example, glycerine. trimethylol propane, pentacrythrilol and the like. may be used. Preferably, the hydroxyl number of the polynlkylene ether alcohol will not be above about 225 and it viill seldom be below about 25.

Any suitable organic polyisocyanate including those disclosed in United States Reissue Patent 24.514 to Hoppe et al. issued August 12, W58. may be u ed. Arylenc cliisocyanates are preferred. such as. for example, 2,4-toluylcne diisoeyanate. 2,ti-toluylene diisocyant'lte, p,p'-diphcnylmethane diisoeyanatc. 1.! naphthalene diisocyanate and the like. Best re ults lttwc been obtained up to this time with an isomeric tui\tuic of about In lti'toluylene diistuyanate and about SW ll-toln -lcuc dtisocyanate.

indicated hcrcinlu'lore. cellular polyurethanes prepared in accordance with the proccss described herein have all of the advantages of cellular polyurethanes prepared from polyalltylene ethcr alcohols heretofore and the added advantape of being more stable against degradation when subjected to high temperatures. For example. it has been found that the product of this invention is stable against any substantial amount of degradation at a temperature of I40" C for more than l hours while cellular polyurethanes prepared from the same reaction components and from the same catalytic compounds but ut different proportions are subject to severe degradation when heated at l l C. for only 2 hours. It is apparent from the results of physical tests made on cellular polyurethanes prepared in accordance with this invention and a cellular polyurethane prepared by the same manipulative steps and from the same components but with a catalyst mi\turc containing a dillcrcnt ratio of tin compound and tertiary amines after heating in a hot air oven that the product of this invention has superior heat stability.

The center of the samples marked (X) had completely decomposed after the heat period converting the original s lid block of cellular polyurethane into a hollow onev the catalysts in the foregoing table designated I. II and Ill are dibutyl tin-ditl cthylhexoatel. N-ethyl morpholine and triethylcnc diamine. respectively. The cellular polyurethanes de ignated Samples A. it and C were all prepared in accordance with the embodiment of Fih'llllPlC l hereinafter except that the catalyst consisted of the amounts of di utyl tin-dill ethylhcxoatc). Nethyl morphohne and tricthylcnc diamine as shown in the table above.

In order better to describe and further clarify the invention. the follot inu are specific embodiments thereof.

Finmplr I n. ally-St ll o L but. I.

wherein (C H O) represents about 17 oxyethylene units and nbout l3 oxypropylenc units: and the vrduc of z is thus about 30. are mixed together substuntitdly simultunc ously with an apparatus oi the type disclosed in US. Patent 2.764.565. All of the components are substantiully uniformly mixed loucthcr suhstuntinlly instuntuncou ly in this npparntus by injecting the ill oignnic diisocyunutc. (2t cntalyst tniout'c and (3| \\'ttl-clbllict ltt mixture as 5LPltl'.tlt slrczuus into the poiyallrylcnc ether nlcohol eing conlinuously le into the uiifint; chnnber the :rppuizuus. the rcsultiug: mi tiue l conti uousl; ii chug 'd trou the uppurntus beloie rtn\ suh-duut ul uount o! clicmicid rcztctit-n bci ccn the L'Ututu ttctdt "cfcd. ("hcnticul rru-gtion proceeds nl'tcr di tint c ol the retiction mixture with accompanying: cx pnusion and foaming of the mi\turc into a eel ulru' product which solidifies to form n cellulnr polyurethane plustic bu ing it density ol' about 2 pounds per cubic loot.

Example 2 About ltltl pu ts by eight of a polyulltylcnc ctlicr triltydric alcohol prepuicd by condenstuion oi propylene otidc and glyccrinc and hitting; a molecuhu weight of ubout .Ultlll uud un hydroxyl number of nbou! '6, about 4t! pails of it mixture of about I l; lh-tcltylenn dil-;OCyttflt.!tC und about 8t); l l-toluylcnc diisocyunutc. :tbout 07h purl of it catalyst mixture containing about (UH port dil utyl tin-dill cthylhexoutc). ubout .5 part N-cthyl morpbolinc, unrl about Ill? part lricthylene diurninc admin 3 parts Witter and ubout I put of Lt compound bu ing the lormulu wherein tf ll 'll represents nbout l7 oxyetlnlcnc units Ltlltl about l3 ox pro nlcne t'ttlls und the vtilue of is thus ubout 3(,l are mflcd together \ubstuntiully simultuneously with ttn appurutus oi the type di-closcd in lib. lutent 3.764.565. ldtxint. is uchicved in the appartuus in the same manner as described in Example I and the resulting cellular polyurethunc. after solidification, lltlS a density of about 2 pounds per cubic foot.

Ernmpl'e 3 shout ltltl parts by weight of a polypropylene ether glycol having a molectllur weight of about 2.tlUtl and an hydroxyl number of about 56. about 98 purts of it mixture of about 80% 2.4-toluylcnc diisocyunatc and about 2.6-toluylcne diisocyunntc. about 1.3 putts of :1 catalyst mixtu e composed ol about ll.l part dibutyl tinditZ ethylhexontct. about 1 part N-cthyl morpholinc und ubout Ill pnrt triethylene diznuinc. about 3 parts water i t about 2 parts of u compound boring the formula wherein (C H OJ represents about l7 oxyethylene units and about ll oxypropylcnc units and the value of z is thus about 0. are mixed lt jlClllLt substztntiully simub tuneously with an uppzirntus oi the type disclosed in US. Patent Lita-L565. The components are mixed together in the apparatus in the manner described in the foregoing cxuniples und alter the mixture has been discharged und cbemicul rct'iction hus proceeded. the resulting ccllulur product has it dens ty ol about 2 pounds per cubic foot and is stable again t degradation ut about 140 (1 for more than 16 hours.

Example 4 A mixture of about parts by weight polypropylene ether trihydric alcohol having an average molecular weight of about 3,000 rind an hydroxyl number of about 56 and prepared by condensation of propylene oxide with glyccrine and :tbout l putts ll MCltllll polypropylene ether glycol having a molecular weight of about 2.000 and an hydroxyl number of about 56 are mixed with about 38 putts by weight of u mixture of 2.4-toluylene diiso- C}i.llltttt [ll'ltl about 20'} 2,6-toluylene diisocyanatc, about 3 pints water. about L3 parts by weight of a Catalyst mixture composed of nbout (Ll part dibutyl tin-dit2-ethyl hcxoatcl. about i pnrt N-cthyl morpholine and about 0.2 part tricthylcnc diumine, and about 1 part oi a silicone compound having the formula ll; 5 1 wherein tf H- ll represents about 17 oxyethylcnc units utld about 13 oxypropylene units and the value of z is thus about 30, are mixed together substantially simultaneously \sith an apparatus of the type disclosed in [1.8. Patent 2.764.565. All of the components are substantially uniformly mixed together substantially instantaneously in this apparatus by injecting the (1) organic diisocyanatc. (2) catalyst mixtuie and (3) water-silicone mixture as separate streams into the polyalkylcnc ether alcohol being continuously led into the mixing chamber of the apparatus. The rcsulling mixture is continuously discharged from the apparutus before any substantial amount of chemical rcaction between the components has proceeded. Chemical reaction proceeds after discharge of the reaction mixture with accompanying expansion and foaming of the mixture into a cellular product which solidifies to form a cellular polyurethane plastic having a density of about 2 pounds per cubic foot. I

It will be understood that any other polyzdkylene ether alcohol disclosed a suitable herein can be substituted for the specific ones used in the foregoing examples. Littewise. any other organic polyisocyanate disclosed as suitable herein may be substituted for the isomeric mixture of toluylenc diisocyzinate used in the examples. Moreover. any other catal st mixture in so long as the components and ratio specified hcreinbeforc are used may be substituted by the specific catalyst mixture used in these examples.

Although all silicone compounds represented by the general formula given hereinbefore are broadly contemplated. best results have been obtained with a compound having the formula \vhcrcin ll Ul is a mixed polyoxyethylene and oxypropylcnc block containing about l7 oxycthylcnc units and about 13 oxypropylcnc units. Hence. it is preferred to use this compound in conjunction with the novel cntalyst set forth herein to prepare a cellular polyurethane. It has been found that the combination of catalyst and silicone provided by this invention can be used to best advantage in preparing a cellular polyurethane from a polyalkylcne ether alcohol havimc a secondary hydroxyl group. such as. for example. a polypropylene ether glycol or the condensation product of propylene oxide and n polyhydric alcohol The density of the product will vary with the amount of water used. Preferably. from about 1.5 to about 5 parts water per parts polyalkylene ether alcohol is used. Preferably, the amount. of organic polyisoeyanate used is an amount about equivalent to the reactive hydrogen atoms of the polyalltylene ether alcohol and water. That is to sny any amount of polyisocyanate from slightly less than the theoretically equivalent amount to an excess over the theoretical amount can be used but an equivalent amount is preferred.

As indicated hercinbet'ore. the catalyst provided by this invention can be used to prepare a cellular polyurethane by reaction of a polyalkylenc cthcr alcohol having a utolccular weight of at least about 500. an organic polyisocyauatc and an inert gas blowing agent under suhstantiab ly anhydrous conditions. Any suitable inert gas or gas producing material, such as. for example. air, carbon dioxide. methylene chloride, nitrogen, dichlorodifiuoromethane. or he like. may be used. The catalyst may be i will in any suitable solvent. The methylene chlo dichlorodilluoromcthanc or other gas producing r att ial may be used as a solvent. Other suitable solvents m) t'ctiiflllf. ethyl acetate, hexane and the like. The gas blowing agent may be any material which is a gas at the temperature at which the foaming reaction occurs. Preferably. the foaming reaction is carried out at a temperature somewhere between room temperature of about 20 C. and about 100 C. Usuall only an amount of polrisocyanate equivalent to the hydrosyl groups of the polynlkylenc ethcr alcohol will be required although any excess over that amount can be used. In fact, the blowinc. might be achieved by a combination of an added inert and gas produced by reaction of water with a polyisocyanate.

The cellular" product provided by this invention is particularly advantageou for use as sponges or in upholstering furniture and for making underlay for carpets. it may also be used in arm rests on the interior of vehicles.

Tricthylcne dinmine has the formula Fxamplcs of suitable trialkyl tin oxides include tricthyl tin oxide, tributyl tin oxide. methyl dibutyl tin oxide. trihesyt tin oxide and the like. Examples of suitable dialkyl tin chlorides. and dinlkyl tin orides include (libutyl tin chloride. dibutyl tin oxide. dihcx l tin chloride. diethyl tin oxide and the like.

Although the tin containing compound can be mixed with the tertiary amines. it is advisable in some instances to mix the tin compound \tith the N-alkyl morpbolinc and the siloxnnc stabilizcr and provide a separate mixture of water and tricthylcne diarninc. The two mixtures are ltlleL'l tl into the polyalkylene etltcr alcohol sparatcly. in other instances, the tin compound. both tertiary amines and the siloxauc can be mixed together and this mixture and water injected into the poiyalkylcne ether alcohol separately.

Although the invention has been de cribed in considerable detail in the foregoing. it is to be UtltlCt'slUOd that such detail is solely for the purpose of illustration and that many variations can be made by those skilled in the art without departing from the spirit and scope of the imentiou except as is set forth in the claims.

What is claimed is:

i. As a new composition of matter. an improved catalyst for chemical lCtlCllUt'h uhich produce a polyurethane foam compri ing (i) a member selected from the group consisting of n trizllkyl tin oxide in which the alkyl groups contain from t to 5 carbon atoms. a dialkyl tin chloride in which the alkyl groups contain from t to 8 carbon atoms. a dialkyl tin oxide in which the all-.yl groups contain from I to 8 carbon atoms and a dialkyl tin alt of a carboxylic acid having from t to 18 carbon atoms in which the all y] groups contain from t to S cnrbon atoms. (2) an N-alkyl morpholine selected from the group consisting of N-ethyl morpholine and N-methyl morpholine and (3) tricthylcne diamine in the ratio of from about 0.01 part to about 01 part of (l) per about 0.2 part to about 1.5 part of (2) and about 0.1 part to about 0.3 part of (3).

2. As a new composition of matter. an improved catalyst for chemical reactions which produce a poly- 8 urethane foam comprising (1) dibutyl tiu-di(2-ethylllL\UttiC). t2) N-etltyl morpholine, and (3) tricthylene diatuinc in the ratio olfrom about 0.0l part to about 0.1 part of (H per about 0.2 part to about L5 part of (Z) and about U.l part to about 0.? part of t3).

I A method for making a cellular polyurethane plastic which comprises reacting an organic polyisocyanate nith a pulyalltylenc ether alcohol having from 2 to 4 hydroxyl groups. a molecular weight of a least about 500 and an hydroxyl number of not more than about 225 in reaction mixture containing an inert gas and a catalyst com rising from about 0.0! part to about 0.1 part of a member selected from the group consisting of a trlalkyl tin ovidc in which the alkyl groups contain from I to 8 carbon atoms. a diall vl tin chloride in which the alkyl groups contain from I to 8 carbon atoms, a dialkyl tin oxide in which the alkvl groups contain from 1 to 8 carbon atoms and a dialltyl tin salt of a carboxylic acid having from t to 18 carbon atoms in which the alkyl utotlps contain from t to 8 carbon atoms, from about 0.2 part to about 1.5 part of an N-alkyl morpholine sclcctcd from the group consisting of N-ethyl morpholine and Nancthyl morpholine and from about 0.1 part to about 03 part triethylene diamine per 100 parts by weight pulyalkylene ether alcohol.

4. A mcthod for making a cellular polyurethane plastic which comprises reacting an organic polyisocyanate, a polyalkylenc ether alcohol having from 2 to 4 hydroxyl groups and a molecular weight of at least about 500 and an hydroxyl number of not more than about 225 and water in a reaction mitture containing front about 0.0! part to about 0.l part of a member selected from the group consisting of a trialkyl tin oxide in which the all}! groups contain from 1 to 8 carbon atoms, a dialkyl tin chloride in which the alkyl groups contain from 1 to 8 carbon atoms. a dialkyl tin oxide in which the alkyl groups contain from t to 8 carbon atoms. and a dialkyl tin salt of a carboxylic acid having from 1 to 18 carbon illll lx in which the alkyl groups contain from 1 to 8 curbon atom front about 0.2 part to about 1.5 part of an N-alkyl morpholinc selected from the group consisting of N-ethyl morpholine and N'methyl morpholine and from about 0.1 part to about 0.3 part triethylcne diamine per 100 parts by weight polyalkylenc ether alcohol.

5. A method for making a cellular polyurethane plastic which Comprises mixing substantially simultaneously an organic polyisocyanate. a polyalkylene ether alcohol having from 2 to 4 hydroxyl groups. a molecular weight of about 3000 and an hydroxyl number of about 56, water and a catalyst comprising from about 0.0] part to about 0.1 part of a member selected from the group consisting of a trialkyl tin oxide in vthich the alkyl groups contain from t to 8 carbon atoms. a dialkyl tin chloride in which the alkyl groups contain from 1 to 8 carbon atoms, a diulkyl tin oxide in which the alkyl groups contain from t to 8 carbon atoms and a dialkyl tin salt of a carboxylic acid having from t to 18 carbon atoms in which the alkyl groups contain from t to 8 carbon atoms, from about 02 part to about 15 part of an N-alkyl morpholine selcctcd from the group consisting of N-ethyl morpholine and N-methyl motpholine and from about 0.1 part to about 03 part triethylcne diamine per 100 parts by weight polyalkylene ether alcohol.

6. The process of claim 5 wherein the tin compound in the catalyst is dibutyl tin-di(2-ethylhcxoate).

7. The process of claim 3 wherein the tin compound is dibutyl tin-ditZ cthylhexoatc).

8. The process of claim 3 wherein the polyalkylene ether alcohol is a triol having a molecular weight of about 3.000 and prepared by condensation of an alkylene oxide having from 2 to 5 carbon atoms and a polyhydric alcohol selected from the group consisting of glycerinc, trimcthylol propane. hexanctriol and triethanolamine.

9. The method of claim 4 wherein the tin compound is dibutyl tin-di(2 cthylhexoate).

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,044,971 July 17, 1962 Samuel Polis It is hereby certified that error appears in the above numbered patent req'liring correction and that the said Letters Patent should read as corrected below.

Column 2, line 33, for "1 to 8 carbon atoms" read 1 to 18 carbon atoms Signed and sealed this 12th day of November 1963.

(SEAL) Altest:

ERNEST W. SWIDER EDWIN L. REYNOLDS Altesting Officer AC ti l'lg Commissioner of Patents 

4. A METHOD FOR MAKING A CELLULAR POLYURETHANE PLASTIC WHICH COMPRISES REACTING AN ORGANIC POLYISOCYANATE, A POLYALKYLENE ETHER ALCOHOL HAVING FROM 2 TO 4 HYDROXYL GROUPS AND A MOLECULAR WEIGHT OF AT LEAST ABOUT 500 AND AN HYDOXYL NUMBER OF NOT MORE THAN ABOUT 225 AND WATER IN A REACTION MIXTURE CONTAINING FROM ABOUT 0.01 PART TO ABOUT 0.1 PART OF A MEMBER SELECTED FROM THE GROUP CONSISTING OF A TRIALKYL TIN OXIDE IN WHICH THE ALKYL GROUPS CONTAIN FROM 1 TO 8 CARBON ATOMS, A DIALKYL TIN CHLORIDE IN WHICH THE ALKYL GROUPS CONTAIN FROM 1 TO 8 CARBON ATOMS, A DIALKYL TIN OXIDE IN WHICH THE ALKYL GROUPS CONTAIN FROM 1 TO 8 CARBON ATOMS, AND A DIALKYL TIN SALT OF A CARBOXYLIC ACID HAVING FROM 1 TO 8 CARBON ATOMS IN WHICH THE ALKYL GROUPS CONTAIN FROM 1 TO 8 CARBON ATOMS, FROM ABOUT 0.2 PARTS TO ABOUT 1.5 PART OF AN N-ALKYL MORPHOLINE SELECTED FROM THE GROUP CONSISTING OF N-ETHYL MORPHOLIEN AND N-METHYL MORPHOLINE AND FROM ABOUT 0.1 PART TO ABOUT 0.3 PART TRIETHYLENE DIAMINE PER 100 PARTS BY WEIGHT POLYALKYLENE ETHER ALCOHOL. 